The legend is that Newton discovered Gravity when he saw a falling apple while thinking about the forces of nature. Whatever really happened, Newton realized that some force must be acting on falling objects like apples because otherwise they would not start moving from rest.
The problem of elephant destroying trees in Southern Africa is due to competition
Chile, Argentina, Brazil, Paraguay
The effect that global warming will have on present day is the increase in average temperature and reduced rainfall. The glaciers around the world will start melting and the sea level will start rising. This will lead to hurricanes and floods. It has the potential to destroy the whole world.